The best practice for this sort of situation is to create a method that hold all the logics, and call the method in both events, rather than calling an event from another event;
Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
LogicMethod()
End Sub
Protected Sub Button2_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
LogicMethod()
End Sub
Private Sub LogicMethod()
// All your logic goes here
End Sub
In case you need the properties of the EventArgs (e), you can easily pass it through parameters in your method, that will avoid errors if ever the sender is of different types. But that won't be a problem in your case, as both senders are of type Button.